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Abstract

Materials engineering and nano-manipulation play a key role in the development of advanced Lithium-Sulphur (Li–S) batteries in terms of energy and power density (both gravimetric and volumetric), cycling stability, rate capability, safety and the cost of production. In this thesis, two strategies are used to address the demands, i.e. fabrication of low cost, environmentally benign and conductive carbon-sulphur (C−S)
nanostructured cathodes, and the use of interlayers as a novel battery configuration in Li–S battery systems.
In the first strategy, inexpensive, scalable, environmentally-friendly and commercial bamboo biochar was activated via a KOH/annealing process to create an abundant microporous structure. This was then used to encapsulate sulphur to prepare a microporous bamboo carbon–sulphur (BC-S) nanocomposite as the cathode for Li–S batteries. The bamboo carbon micropores can encapsulate sulphur and polysulphides
to reduce the shuttle phenomenon during cycling while simultaneously maintaining electrical contact between the sulphur and the conductive carbon framework during the charge/discharge process. The treated BC-S (T_BC-S) nanocomposite with 50 wt% sulphur content delivers a high initial capacity of 1295 mA·h·g−1 at a low discharge rate of 160 mA·g−1 and high capacity retention of 550 mA·h·g−1 after 150 cycles at a high discharge rate of 800 mA·g−1 with excellent coulombic efficiency (≥ 95%).